A Halbach array is an arrangement of magnets that enhances the magnetic field on one side of the array while largely minimizing, through cancellation, the magnetic field on the opposite side of the array. Successive magnets in the array are rotated in a specific sequence of orientations, which results in the magnetic fields of the magnets comprising the array to combine in ways that enhance the resulting (i.e., net or combined) magnetic on one side of the array, while minimizing the magnet field on the other side.
Motors comprising Halbach array rotors are known. In one class of motor, a stator comprising an iron core wrap in windings operates as a stationary electromagnet. An interior rotor comprising a Halbach array of permanent magnets arranged in a cylindrical array such that the magnetic field of the rotor is concentrated on the outside of the array is provided. Voltages are applied to the respective windings of the stator to generate magnetic forces that interact with the enhanced outer magnetic field of the rotor to cause the rotor to rotate about a longitudinal access of rotation. The rotor typically is coupled mechanically to a shaft or other structure to transmit the torque to a load, such as an aircraft lift fan, propeller, or some other load.
In the typical approach, the magnets comprising the Halbach array of such a rotor have been substantially rectangular in shape, and have been arranged with the longitudinal axis of the magnets substantially aligned (i.e., parallel) with the axis of rotation of the rotor.